You need to push back against whoever is rooting for the advertisements hard. An advertisement has to be seen to be of any value. No successful app has the primary function of displaying ads (broad generalization, but mostly true). By making the user scroll past the ads to get main function of the app, you're pretty much guaranteeing the user will do that: scroll right past the ads, notably without reading or clicking on any of them.
Also, displaying 8 ads at once is pretty bad, but 5-7 rows of ads? At 4 per row? You really expect someone to take in 20-28 ads at once?
Maybe you remember tales of the $1,000,000 website, a successful, single-purpose advertising website. Ads on that site probably paid off since the site was such a novelty when it debuted in 2005. The creator really got their million bucks and the advertisers got their eyeballs. But looking at that wall of ads... do you really think there's anything worth finding in there?
Your static grid of adverts reminds me of one of the oldest advertising schemes still in existence: the yellow pages. You open up the phone book looking for businesses by category and are confronted with full pages of ads. This was wildly successful advertising when it debuted over a hundred years ago because:
- it was the only means of semi-permanent, mass-distributed adverts
- there was literally no other way to find businesses
- people who saw an ad there were likely already looking for the product or service being advertised, because the book and ads are organized by category/keyword.
Today, this would be referred to as targeting motivated shoppers. The yellow pages are essentially an analog search engine. No one bought an ad for toupeés and placed it in the section women's shoes. Similarly, no one printed ads for toilet repairs in their novellas. To be blunt, the Yellow Pages' scheme will not work for your app.
If you want your ads to be seen, make them visible while the user while they use your app. Not before or after. If you want your ads to be effective, make them targeted and relevant to the user.
Consider Flappy Bird, which earned up to $50,000 per day in advertising. It did this with a rotating ad shown in the footer. Combined with addictive game play and a viral word-of-mouth spread, this guaranteed thousands of people were looking at the ads for hours on end, rather than just a few seconds between opening the app and scrolling or clicking through to the game play.
To sum up, I suggest displaying fewer ads at once (ideally only one), visible 100% of the time that a user is on your compelling interactive feature without impeding use of the app as that will only annoy your users and create negative associations with your advertisers. Targeting these ads ensure that an advertiser reaches their demographic and doesn't waste their time or money reaching people who aren't interested in their products. If you need more impressions, rotate the ad displayed, either every time the app is opened or on a delay while the user is using it.